Generally speaking, the present invention pertains to improvements in a timing mechanism wherein coupled drum wheels of a digital interval timer are rotatably set at a predetermined period of time; wherein at least one cam having a notch opening to an outer periphery of the cam is rotatably coupled to at least one of the drum wheels; and wherein an actuator means engages the cam to open and close electrical switches, the switches being opened when the actuator means drops into the notch; one improvement characterized by the cam and the actuator means being operably associated with each other so that the drum wheels may be rotated in either direction after the electrical switch has been opened.
Another improvement relates to a means providing an auxiliary program for the mechanism which, in general, comprises a drum shaped helical cam, means applying power driven rotation to the drum shaped helical cam, a cam follower engaging the drum shaped helical cam, at least one electrical switch opened and closed by the cam follower, and actuator means causing relative movement between the helical cam and the cam follower.
Another improvement relates to a case for the timing mechanism which, in general, comprises a cup shaped member having a base portion, a pair of side walls, a pair of end walls, and an open end, a base plate closing the open end and having an opening through which the drum wheels protrude, individual ribs in the side walls each having slots therein, individual plates carried in the slots and means carried by the plates receiving the drum wheels and the drum shaped helical cam, and apertures in the base portion receiving electrical terminals carried by the base portion, and at least one output member from a gear train of a motor drive means carried by the base portion.
The present invention relates to a timing mechanism and more particularly to a timing mechanism using a digital interval timer. Timing mechanisms utilizing digital interval timers have been used for many years in appliances such as ovens and ranges and in recent years in appliances such as microwave ovens.
In most, if not all of such applications, drum wheels having coded indicia to indicate time are rotatably coupled together through commonly used geneva gear drives. Also cams are usually coupled to the drum wheels for rotation with the wheels to open and close electrical switches. Such cams usually employ a notch to actuate a cam follower with the cam follower falling into the notch. One of the problems with such an arrangement is that of being unable to rotate the drum wheels in either direction when the cam follower is in the notch. This then causes the operator, in many instances, to rotate the drum wheels many turns when a new time needs to be set.
In microwave oven applications, it has been found to be, at times, necessary to provide an auxiliary program in addition to the normal program usually required for cooking times. More specifically, it has been found to be highly desirable, if not necessary, to vary the power to the magnetron of the microwaven oven during certain cooking time periods.
The type of timing mechanisms discussed herein also have a "packaging problem" in that they are inherently complicated and therefore somewhat difficult to assemble.
The present invention is directed to features of digital interval timing mechanisms which solve these problems.